Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) is a soft ionization method that is widely used in the analysis of large biomolecules such as proteins. An advantage for this technique is the production of singly charged species as this simplifies the analysis of large molecules. Although MALDI-MS has revolutionized the way high-molecular weight compounds are identified, small molecule identification has lagged behind. This is due to the fact that the majority of conventional matrices are small organic molecules, which interfere with the analysis of low-molecular weight (<1000 Da) compounds. Consequently, there is a need to design matrices that would reduce the matrix-background noise and/or increase the signal to noise ratio in the lower mass range.1,2 
Detonation nanodiamonds (NDs) are produced by detonation of 2,4,6-trinitrotoluene (TNT) and Hexogen (RDX) in a closed system in the absence of oxygen. Nanodiamonds have a very narrow molecular distribution and an average diameter of about 4-5 nm. Additionally, they have excellent optical and mechanical properties. Depending on the quenching method used, the nanodiamond surface may have a variety of functional groups which upon oxidation give carboxylated nanodiamonds (Scheme 1). On the other hand, reduction processes introduce hydroxyl groups on the surface, as shown below in Scheme 1. Such oxidized or reduced forms of the nanodiamonds allow for variation in the possibilities of what can be grafted on the nanodiamond surface.3,4
